Connection of through-wall fittings which produce a fluid-tight seal between the outer wall of a conduit and a through-wall opening has produced a variety of different pipe connecters and couplings. Some of the connecting structures have been of a permanent variety which include welding or bonding of the exterior wall of the conduit to the wall opening through which the conduit extends. The use of a permanent bond has several disadvantages. First, The wall through which the opening is formed and the conduit itself are usually formed of dissimilar materials which may not be bondable together. Second, the bonding process is generally time consuming and therefore may be expensive to install even though the materials used may be relatively inexpensive.
The preferred variety of connector is that of a compression coupling using elastomeric materials which are joined about the circumference of the conduit and are then connected in a fluid-tight manner to the wall through which the conduit passes.
For example, the coupling structure of Kunz in U.S. Pat. No. 3,973,789 discloses an elastomeric sleeve installed about the through-wall conduit which is compressed by the use of a washer which is threadably connected to the sleeve. While such a connection may be useful in the particular application envisioned by Kunz where a threadable pipe member is used, such a coupling structure is inappropriate for non-threadable materials or in situations where it is not expedient or desirable to cut threads on the pipe material.
In view of the foregoing it can be seen that there is a need for a through-wall coupling which is useful for providing a fluid-tight fitting between a conduit and the walls through which the conduit extends the conduit is unthreaded.